1. Field of the Invention
The present invention relates to a power converter, and more particularly, to a control circuit of the power converter.
2. Description of Related Art
Various power converters have been widely used to provide regulated voltage and current. In order to reduce the device count and cost of the power converter, primary-side control technologies have been proposed, such as “Close-loop PWM controller for primary-side controlled power converters” by Yang, et al., U.S. Pat. No. 7,016,204; and “Apparatus and method thereof for measuring output current from primary side of power converter” by Yang, et al., U.S. Pat. No. 7,061,225, etc. However, these prior arts are developed for operating under discontinuous current mode (DCM), which may lower the power efficiency of the power converter. The illustration of the discontinuous current mode and continuous current mode (CCM) can be found in the “Adaptive slope compensator for current mode power converters” by Yang, U.S. Pat. No. 5,903,452.
It is hence important to develop an output current control circuit that can be operated at continuous current mode for achieving higher power efficiency of the power converter.